Light emission spectroscopy from metal electrodes during electrolysis

Light emission from the metal electrodes cathodically polarized at cell vol tages up to 250 V was investigated in various aqueous electrolyte solutions . The light emission was observed when the temperature of electrodes exceed ed the boiling temperature of the electrolyte due to the intense cathodic p olarization: a thin vapor layer was formed at the metal / electrolyte inter face in which a high electric field ionized vapor molecules to generate the plasma state. The light emission was caused by a glow discharge at relativ ely low cell voltages and by a spark discharge at high cell voltages. The s pectra of the emitted light were assigned to the constituents of the electr olyte solution, electrode material and gaseous hydrogen evolved at the elec trode.